The present invention relates to the field of displaying images and data. More specifically, the present invention relates to the field of large area displays.
Currently, there is a wide variety of devices and techniques utilized to visually display analog and/or digital signals containing moving images, data, and the like, thereby enabling people to view this information. Many of these display devices are very familiar to the general public. For instance, moving images and data are visually displayed on television sets, computer monitors, and arcade video games, to name a few. It should be appreciated that there are many different technologies which are utilized to implement these type of display devices. Some of these technologies include a cathode ray tube (CRT), a liquid crystal display (LCD), a laser based system, a reflective LCD, and a plasma display.
Furthermore, there are other existing techniques and technologies which are utilized to display moving images and data on a much larger scale than those mention above. For example, one technique for generating a large area display involves fabricating a xe2x80x9cPowerWallxe2x80x9d which is made-up of an array of projectors, each displaying a specific portion of the overall viewable image. Another technique for generating a large area display is similar to the PowerWall approach, except it involves the use of CRT monitors instead of projectors. Basically, a large area display is generated by utilizing an array of image projectors, each projecting a specific portion of the overall viewable image onto a desired surface. This technique is commonly referred to as xe2x80x9ctilingxe2x80x9d.
In order to more fully understand how a prior art large area display is generated utilizing tiled image projectors, a more detail description is presented. For simplicity, the generation of a single projected image by an image projector is initially described. It should be appreciated that each image projector generating a portion of the large area display operates in the same fashion. FIG. 1A is a diagram illustrating the manner in which a projected image 100 is typically generated by a prior art image projector (not shown), which is well known by those of ordinary skill in the art. Fundamentally, the image projector raster scans or xe2x80x9cdrawsxe2x80x9d the pixels of image 100 in a row, from left to right. Furthermore, the image projector raster scans the rows of pixels of image 100 from top to bottom. Once the bottom row of pixels of image 100 is raster scanned, the image projector returns to the upper left-hand corner to begin raster scanning the top row of pixels again. In this fashion, the image projector continually generates and updates image 100 by repeating the process described above.
Specifically, to generate projected image 100, the image projector starts raster scanning pixel 102, which is located in the upper left-hand corner of image 100. The image projector proceeds to raster scan all of the pixels, from left to right, located in the top row of image 100. Upon reaching pixel 104, which is the right most pixel of the top row, the image projector stops raster scanning and proceeds to the left-hand edge of image 100 to begin raster scanning the next row of pixels. The image projector continues this process for each subsequent row of pixels until it reaches pixel 106, located in the lower right-hand corner of image 100. Upon raster scanning pixel 106, the image projector stops raster scanning and returns to pixel 102 to repeat the raster scanning process described above. In this manner, the image projector continually generates and updates image 100.
Now referring to FIG. 1B, which is a diagram illustrating a prior art manner of generating a typical large area display 120 by tiling projected images 100, 122, 124, and 126, which in combination result in a large viewable image. It should be appreciated that four image projectors (not shown) are utilized to generate projected images 100, 122, 124, and 126. Furthermore, it should be appreciated that each image projector generates one of projected images 100, 122, 124, and 126. It should be further appreciated that projected images 122-126 are each generated in the same manner as projected image 100, as described above. Specifically, at time equal to zero, all four image projectors simultaneously begin raster scanning, from left to right, the top rows of pixels of projected images 100, 122, 124, and 126. Furthermore, the image projectors raster scan the rows of pixels of images 100, 122, 124, and 126 from top to bottom. Once the bottom rows of pixels of images 100, 122, 124, and 126 are raster scanned, the image projectors repeat this process in order to continuously update and generate large area display 120.
There are disadvantages associated with the prior art technique of tiling multiple image projectors to generate a large area display, as described above. One of the main disadvantages is that it produces images exhibiting visual defects or anomalies which are particularly evident along the horizontal seams located between the projected images (e.g., 100, 122, 124, and 126). Furthermore, these visual anomalies are more pronounced when certain images (e.g., visual simulation) are being displayed. The occurrence of these visual anomalies are attributed to the fact that the pixels near the horizontal seams are temporally out of phase.
For example, as the lower rows of pixels of images 100 and 122 are raster scanned displaying the end of a frame of data, the upper rows of pixels of images 124 and 126 are raster scanned around the same time displaying the beginning of a subsequent frame of data. As such, two different frames of data coexist near the horizontal seam of images 100, 122, 124 and 126. Therefore, the pixels near the horizontal seam of images 100, 122, 124, and 126 are temporally out of phase. As such, an image appears to xe2x80x9ctearxe2x80x9d as it is displayed moving horizontally across large area display 120 along the horizontal seam between images 100, 122, 124, and 126 because the human eye integrates the image generated by pixels that are illuminated at approximately the same time (see FIG. 1C). Pixel 106 is illuminated near the end of each frame, whereas pixel 128 is illuminated near the start of each frame. As such, it is apparent in FIG. 1C that the image information for frame 0 for pixel 106 will get integrated with frame 1 information for pixel 128. This means that an object that is moving horizontally along the horizontal seam will have some pixels from one frame and other pixels sampled from the subsequent frame. The motion of the object will tear the overall image. Note that the pixel is really only bright when the scan beam hits the pixel, then the phosphor""s light emission decays fairly rapidly. Much of the image retention is in the workings of the human eye. In other words, psycho-visual anomalies are generated by this prior art tiling technique since the pixels near the horizontal seams are temporally out of phase.
Accordingly, a need exists for a method and system for tiling multiple image projectors to generate a large area display of moving images and data which does not exhibit visual defects or anomalies.
The present invention provides a method and system for tiling multiple image projectors to generate a large area display of moving images and data which is free of visual defects or anomalies. Therefore, the present invention is able to produce large area displays exhibiting more realistic and lifelike images thereby improving the viewing experience of the viewer.
Specifically, one embodiment of the present invention includes a system for generating a large area display of moving data. The system comprises a display image generator for rendering pixels of an image to be displayed as the large area display. Furthermore, a plurality of tiled image projectors are coupled to the display image generator to receive pixel data and to generate the large area display. The plurality of tiled image projectors comprise at least two image projectors. A first image projector which performs a first type of raster scanning sequence to display a first portion of the pixel data. Moreover, a second image projector which performs a second type of raster scanning sequence to display a second portion of the pixel data, wherein the second type of raster scanning sequence is different than the first type of raster scanning sequence.
In another embodiment, the system comprises a display image generator for rendering pixels of an image to be displayed as the large area display. The display image generator comprises a host processor having an application program issuing graphics commands and a geometry circuit coupled to the host processor for processing primitives. Furthermore, the display image generator also comprises a rasterizer circuit coupled to the geometry circuit for generating pixel data and a frame buffer coupled to the rasterizer circuit which stores the pixel data. Moreover, the display image generator also comprises a display interface circuit coupled to the rasterizer circuit to output the pixel data. The system also comprises a plurality of tiled image projectors coupled to the display interface circuit to receive the pixel data and to generate the large area display. The plurality of tiled image projectors comprise at least two image projectors. A first image projector which performs a first type of raster scanning sequence to display a first portion of the pixel data. Furthermore, a second image projector which performs a second type of raster scanning sequence to display a second portion of the pixel data, wherein the second type of raster scanning sequence is different than the first type of raster scanning sequence. It should be appreciated that the display interface circuit is able to access the pixel data from the frame buffer in any order or sequence (e.g., reverse order) for output to the plurality of tiled image projectors.
In still another embodiment, the present invention includes a method for generating a large area display of moving data. The method comprises the step of rendering pixels of an image to be displayed as the large area display. The method also includes the step of storing pixel data within a memory device. Another step of the method includes outputting a first and second portions of the pixel data to a plurality of tiled image projectors. The method also includes the step of performing a first type of raster scanning sequence to display the first portion of the pixel data. Another step of the method includes performing a second type of raster scanning sequence to display the second portion of the pixel data, wherein the second type of raster scanning sequence is different than the first type of raster scanning sequence.
These and other advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the drawing figures.